Background: There has been no treatment found yet that cure dementia. Hence it is important to establish the evaluation index of cognitive decline before becoming dementia. Objective: The purpose of this study was to clarify the effective balance test indicating early cognitive decline by gender. Methods: A total of 218 volunteers (60 years of age and above) who participated in the Iwaki promotion health project in 2015 were recruited. We performed three balance tests: one leg standing test, functional reach test and static posturography, and we used mini-mental state examination (MMSE) to investigate cognitive function. Results: As a result of analysis of covariance, there was a statistically significant trend in only men that the more the MMSE score declined, the longer became the path length with both eyes opened and closed. In the result of multiple regression analysis, there was a significant negative association with MMSE score and path length with eyes opened or closed in men. There was no significant association with MMSE scores and balance tests in women. Conclusion: The study suggests that static posturography might be a useful balance test to assess early cognitive decline in men.

Single nucleotide polymorphisms in mitochondrial DNA, such as mitochondrial 1555 A>G (m.1555 A>G) and mitochondrial 1494 C>T (m.1494 C>T), are known to be causative mutations of nonsyndromic hearing loss following exposure to aminoglycoside antibiotics. The prevalence of the m.1555 A>G and m.1494 C>T mutations has not been reported for the general population in Japan. The purpose of this study was to investigate the prevalence of m.1555 A>G and m.1494 C>T mutations in a community-dwelling population in Japan in order to prevent aminoglycoside-induced hearing loss. We recruited participants older than 20 years of age to the Iwaki Health Promotion Project in 2014, 2015, and 2016, resulting in the recruitment of 1,683 participants. For each participant, we performed a hearing test and a genetic test for the m.1555 A>G and m.1494 C>T mutations using the TaqMan genotyping method. The m.1555 A>G mutation was detected in only 1 of the 1,683 participants (0.06%). This carrier of the m.1555 A>G mutation was a 69-year-old male with bilateral, symmetric, and high-frequency hearing loss. We provided genetic counseling and distributed a drug card advising him to avoid the administration of aminoglycoside antibiotics. In contrast, the m.1494 C>T mutation was not detected in this study population.

Purpose: To determine the prevalence of perilymphatic fistula (PLF) in sudden-onset sensorineural hearing loss (SSNHL) patients by employing the Cochlin-tomoprotein (CTP) detection test, a specific diagnostic marker for perilymph. We also analyzed the clinical characteristics associated with hearing outcomes in this cohort. Methods: A total of 74 eligible patients were prospectively enrolled. Following myringotomy, middle ear lavage (MEL) samples underwent the CTP test to identify perilymph leakage. Intratympanic dexamethasone (IT-DEX) therapy was administered, and hearing outcomes were assessed. Control groups comprised patients with chronic otitis media (n = 40) and non-inflammatory middle ears (n = 51) with concurrent MEL sample collection. Results: CTP was positive in 16 (22%) patients. No control samples showed positive results. Multiple regression analysis indicated that age and pre-treatment hearing levels significantly contributed to the CTP value. We found a positive correlation between CTP values, age, and pre-treatment pure-tone averages. Notably, CTP values in SSNHL cases aged 60 and above were significantly higher than in those below 60 years. Patients with positive CTP had significantly worse recovery rates after IT-DEX treatment. Conclusion: This study is the first prospective investigation demonstrating a positive relationship between CTP values, age, and hearing severity in SSNHL, indicating that PLF might be the essential cause of SSNHL, particularly in the elderly. Our findings suggest that IT-DEX may be less effective for PLF-associated SSNHL. Future research could reveal that PLF repair surgery is a viable treatment strategy for SSNHL. This study was registered under the UMIN Clinical Trials Registry (UMIN000010837) on 30/May/2013.

Age-related hearing loss (ARHL) is a complex multifactorial disorder. Studies in animals, including mitochondria-mutator mice, and in human suggest that oxidative stress and mitochondrial disturbance play an important role in the pathoetiology of ARHL. Mitochondrial DNA (mtDNA) haplogroups are populations with genetically similar traits, and they have been reported to affect the mitochondrial function of oxidative phosphorylation. To gain further insights into the relationships between mitochondrial haplotypes and the susceptibility to cochlear aging, in this study, we aimed to elucidate how the differences in mtDNA haplogroups may affect ARHL development in Japanese general population. We focused on early onset ARHL, as the same mtDNA haplogroup can show either a negative or positive effect on systemic co-morbidities of ARHL that appear later in life. A total of 1167 participants of the Iwaki Health Promotion Project were surveyed in 2014, and 12 major haplotype groups (D4a, D4b, D5, G1, G2, M7a, M7b, A, B4, B5, N9, and F) were selected for the analysis. A total of 698 subjects aged 30 to 65 years were included in the statistical analysis, and the hearing loss group consisted of 112 males (40.3%) and 111 females (26.4%). Multiple logistic regression analysis showed that the male subjects belonging to haplogroup A had a significantly increased risk of hearing loss, whereas the female subjects belonging to haplogroup N9 had a significantly decreased risk of hearing loss. These results suggested that the mtDNA haplogroup may be an indicator for future risk of morbidity associated with ARHL.